If the estimated distance from Earth to the Coma Cluster of galaxies is about 300 million ly (see Figure 23-21 of Universe, 11th ed.(in the text)), what is its velocity of recession?

Question

Quizplus · Accepted Answer

The velocity of recession of galaxies can be estimated using Hubble's Law, which states that the velocity of recession (v) is directly proportional to the distance (d) from us, with the proportionality constant being the Hubble constant (H0). The Hubble constant is approximately 70 km/s/Mpc. Converting 300 million light-years to megaparsecs (1 Mpc ≈ 3.26 million light-years), we get approximately 92 Mpc. Using Hubble's Law (v = H0 * d), the velocity of recession is thus approximately 70 km/s/Mpc * 92 Mpc = 6440 km/s, which is closest to the given option of 6600 km/s.

If the Estimated Distance from Earth to the Coma Cluster